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"Negative Ion" Generator

Discussion in 'High Voltage' started by Sceadwian, Dec 28, 2010.

  1. Sceadwian

    Sceadwian Banned

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    120VAC (7.5kV Output) Negative Ion Generator-The Electronic Goldmine

    Anyone have any comments on these type of modules? I have no intention of using this for 'negative ion' generation, as ozone is generally bad for people's health, but it looks like a good cheap source of very low current high voltage. It was basically filler for ordering something else that I wanted to make the minimum.

    My question is how do they work? I don't have it yet and I can't read the chips part number to get any real details of the module itself. I'm assuming it's a very low current generator of high voltage DC, but I'm curious as to it's internal circuitry and limitations, primarily what it's safety features are, I like robust toys so I'm kind of hoping it's short circuit / thermally or otherwise failsafe protected.
     
  2. Reloadron

    Reloadron Well-Known Member Most Helpful Member

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    I would venture a guess the unit you linked to would be something like the attached image. There are also versions like this one.

    Years ago I saw the same circuits used to reduce the static charge build up on large rolls of poly film on big printing machines. Commercial units like this had about a 10MΩ resistor in series with the outputs to reduce the shock hazard.

    Anyway, they amount to a high voltage very low current source.

    Just My Take
    Ron
     

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  3. Sceadwian

    Sceadwian Banned

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    Gives me hope Ron. That's exactly what I'm looking for.

    Should have ordered two. Based on input/output voltages from mains, I'm now VERY curious about increasing the frequency.
     
    Last edited: Dec 28, 2010
  4. dave

    Dave New Member

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  5. Reloadron

    Reloadron Well-Known Member Most Helpful Member

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    The ones that just voltage multiply the mains are fairly straight forward. The units that use a 555 get a little tricky. The circuit in the link goes back a few decades I would guess as Popular Electronics hasn't been around for awhile. I would guess that circuit runs at about 1 KHz. The real ***** when trying to build one is trying to find a transformer that will work (unless you have great patience and wind your own).

    I don't know how high you could get the osc frequency before the transformer wouldn't like it. Years ago a good source of high voltage transformers was salvage the flyback transformer out of old B&W CRT TVs before high voltage doubler/tripler were heard of.

    Ron
     
  6. Sceadwian

    Sceadwian Banned

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    This thing operates directly off of mains and outputs HV, it's a single monolithic chip with three wires. It's about as simple as you can possibly get, which leads me to believe it's a monolithic version of the capacitor/diode type HV multiplier, or some variation of it that I'm not familiar with, but until I get it (Wednesday next week) I'm just shooting in the dark. The model number from Electronics Goldmine is useless and the picture is too low res to read the actual chip markings. I haven't hunkered down to search Google for what it might be yet though.
     
  7. Sceadwian

    Sceadwian Banned

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    Did a little more research and these things put out REALLY low current, which is fine I'm curious as to how to go about measuring it's actual output though, both voltage and current. I've never really dealt with any type of high voltage circuits before, s'why I picked up a tiny little one to toy with.
     
  8. Reloadron

    Reloadron Well-Known Member Most Helpful Member

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    Maybe measure the output with a very, very, high impedance high voltage probe?

    Ron
     
  9. Sceadwian

    Sceadwian Banned

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    Well that goes without saying reloadron, I don't have such a probe floating around the house though =) I'm thinking about practical methods that a general hobbyist might have available. I know I can't use carbon resistors, but I do have some 1% thin film resistors. I'm just more than a little wary of having that high a voltage near my meters, it's not a high quality meter or anything but the last time I got my meter near a high voltage source it was dead half a second later.

    Cute story actually. I was curious and bored and put a sheet of tin foil across a 36" TV to see what kind of AC coupling existed, was reading some AC voltage on it, knew my meter was accurate because I'm sure whatever frequency was coming off the tube was NOT in the range the meter could pickup but wanted to see anyways. Decided I was done, but turned the TV off before I disconnected the meter/sheet, there was an audible crack as the capacitance discharged through the meter, it never recovered, I did an autopsy later, no marks no fuses blown nothing, looks like the HV discharge took out the meters main chip (this was not an expensive meter it had little protection circuitry)

    One thing I did think of while mulling this over that would be perfect for measuring the peak voltage would be a bifoil voltage meter. I've seen them before, it's just two strips of aluminum foil of a specific size bound at one end. Attach HV source and the foils charge up pushing away from each other as the charge collects, not sure how you'd calibrate it though. I just want to see to within 500 volts what the peak voltage is, and if possible be able to test it under load to measure it's current output at various loads. I like to characterize things as best I can.
     
  10. Reloadron

    Reloadron Well-Known Member Most Helpful Member

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    You may want to start with a Google of "leyden jar" which I think is what you are after with the aluminum foil strips.

    As to a HV probe you could duplicate something like this. They say 6 KV but it is a 1000:1 probe and the circuit is in the manual linked. Like most it is designed to work into a 10 MΩ input impedance meter.

    I know the deal with experiments gone amuck. Loved the story of the CRT and foil. The classic of everything worked good right till..... :)

    Ron
     
  11. ericgibbs

    ericgibbs Well-Known Member Most Helpful Member

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    hi Ron,
    A Leyden jar is used as a capacitor, I think you mean an electroscope.

    electroscope - Google Search
     
  12. Reloadron

    Reloadron Well-Known Member Most Helpful Member

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    Gawd, I love this place. When I don't know what I mean we have guys like Eric to tell me what I mean. Thank you Eric once again. Leaves, jars? I would go back and find a big pile or resistors and opt for option #2. :)

    Thanks Eric
    Ron
     
  13. 4pyros

    4pyros Well-Known Member Most Helpful Member

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    Normally you would measure the input and use math to determine the output. Andy
     
  14. Sceadwian

    Sceadwian Banned

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    That's if I can find information about the IC pyros, without detailed information on it's efficiency measuring the input power won't do any good. It could be determined by measuring the temperature of the package and working out the amount of energy spent as heat vs input power to determine efficiency but that would require very accurate thermal calculations.
     
  15. 4pyros

    4pyros Well-Known Member Most Helpful Member

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    OK..... Maybe you could measure one the safty resistors on the output. If you use three that would be 1/3 of the voltage and use the value of the resister to get amps. Andy
     
  16. Sceadwian

    Sceadwian Banned

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    Right as soon as I order enough resistors... resistor strings for HV isn't just as simple as a single resistor, you have to use chains of them to lower the actual potential across each resitsor. I only have 4 1meg resistors right now, not enough, probably load the output too much as well.
     
  17. scaecrow

    scaecrow New Member

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    Mr. Sceadwian, I have some hv res - so high I can't measure them. Came from a hvps that lit 4 "gas" lamps for a copier. The supply weighed 50lbs - substantial for a copier. I'll trade you for looking at a very basic (for you anyway) circuit to make sure the components are sized correctly for the load. I am worried about the transistor - not sure how to figure out the base current if I change the trans to one with higher limits of power. My meter says that I have .16 a that will flow throgh it, think that equates to 1.92 w - too close for it's power rating of 2w. Live in Walworth and can deliver. Circuit came from MikeMi.
    315-986-1363
     

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